How bacteria cause disease Flashcards
What leads to different pathotypes in E.coli
Acquisition of pathogenicity islands
UHEC
Enterohemorrhagic E.coli
EPEC
Enteropathic E.coli
UPEC
Uropathogenic E.coli
What is an endogenous infection
Commensal microbiota getting in the wrong place
What is an exogenous infection
Infection from pathogens from the environment
Examples of endogenous infection (PHOM)
Pneumococcal pneumonia
Honeymoon cystitis
Oral strep and endocarditis
Meningococcal meningitis
Routes of exogenous encounter and examples
Respiratory (TB)
Faecal-Oral (Shigellosis)
Venereal spread (syphilis)
Inanimate and animate vectors
What is ingress
Enter through already open channels
What is penetration
Entry through artificial openings
Is Vibrio cholera ingress or penetration
Pure ingress
Is shigella dusenteriae ingress or penentration?
Invade cells lining GI tract
Is S. Typhi, ingress or penetration
invade cells and further into blood supply
Exogenous infection: Zoonoses
Tsetse fly and African sleeping sickness (Trypanasoma bruceii)
Cattle and anthrax (B. anthracis)
Fleas and plague (Y. pestis)
What does iatrogenic mean
Illness or injury occuring unintentionally during medical treatment or diagnosis
Iatrogenic examples
Blood transfusions - syphilis and brucellosis
Contaminated medical devices with CoNS
Describe the Type 3 secretion system of Salmonella
Acts like mini hypodermic needle.
1. Encounter M cells in GI tract and adheses.
2. Inject effectors which cause ruffling, bacteria is engulfed and taken up in vacoule.
3. Another type 3 system allows escape from vacoule
Spread/avade techniques: S. aureus
Inhibits opsonisation, inhibits chemotaxis and kills phagocutes
What part of Streptococcus pneumoniae inhibts phagocytosis?
Capsule
What bacterium inhibits lysosomal fusion
M. tuberculosis
Features Streptococcus pyogenes:
- Capsule – hyaluronic acid, similar to host connective tissue.
- Leukocidins- Streptolysin O/S and NADase
- Degradation of host tissue/other barriers: Hyaluronidase (connective tissue), streptokinase (clots), streptodornase (DNA) and proteases.
Inoxication illnesses (foodborne) are caused by products of what bacteria
S.aureus
B. cereus
C. botulinum
What are AB toxins?
Dimers with active component A and binding component B
Three methods of action of AB toxin
Inhibition of protein synthesis- C diptheriae
Hyperactivation- V. chlorea
Effects on nerve-muscle transmission- C.tetani
Two types of immunopathogenesis
Superantigen - binds TCR to MHC molecule, prevents response
LPS- Overide of reaction, leads to toxic shock
What type of twin is more likely to have both kids have TB
Monozygotic
The two tissue types associated with the two types of leprosy
HLA DR3: Tuberculoid leprosy
HLA DQ1: Lepromatous leprosy
Causative agent of psittcosis and what factor increases risk
Chlamydophilia psitacci infects birds, stress causes birds to shed bacteria.
What bacteria are neonates and young infants at risk to
Bordetella pertussis
What disease can be reactivated at old age
TB
What was MDR TB resistant to
First line agents like rifampicin and isoniazid
What is XDR TB resistant to?
Quinolones and second line injectables
What can bacterial pneumonia be caused by?
S. aureus
H. infleunzae
K. pneuomaniae
P. areuginosa
S. pneumoniae
Synergy examples
Flu + bacterial pnue.
HIV + TB
COVID19 + bacterial pnue.
